This invention pertains to the art of valves and more particularly to high pressure valves.
The invention is particularly applicable to high pressure valves of the type which include a non-rotating valve needle and will be described with particular reference thereto; however, it will be appreciated by those skilled in the art that the invention has broader applications and may be used in other apparatus and environments.
Heretofore, there have been a number of prior high pressure valves of the type to which the subject invention is particularly directed. Typical of these are the valves shown in the commonly assigned U.S. Pat. Nos. 3,679,169 and 3,761,053, the teachings of which are incorporated hereinto by reference. In these prior valves, however, the necessity for changing certain design and operational characteristics has become apparent.
For example, prior valves have employed an actuating stem including a bifurcated inner end which receives the uppermost end of the valve needle in a manner to permit relative rotation therebetween so that as the actuating stem is rotated in cooperating threads to obtain axial movement thereof, the valve needle will not be rotated but simply be moved in an axial direction. To retain the valve needle in a coaxial relationship with the actuating stem so that proper seating of the needle against the valve seat would be obtained and to prevent distortion of the bifurcated area thereof, it was found preferable to include a retaining ring surrounding the lowermost end of the bifurcated stem area.
An alignment bushing disposed between the innermost end of the valve packing nut and the stem or needle sealing medium is required for purposes of placing the necessary and desired compressive force against the sealing medium to obtain the desired sealing characteristics. Furthermore, the alignment bushing functions as alignment means for the valve needle so that the needle will be retained in a coaxial relationship with the valve chamber. To accomplish this, prior valve designs have employed alignment bushings dimensioned to be closely received in that portion of the valve bore receiving the sealing medium so that positive valve needle alignment could be obtained. The necessity for maintaining close tolerances between the bore and the lead end of the alignment bushing caused some difficulty in obtaining the desired relationship between the components and has added some additional manufacturing cost to the valve structure.
Prior valve designs of the general type to which the subject invention is particularly directed have typically employed a bronze bushing or liner disposed between the packing nut and actuating stem with bushing and stem being in threaded communication with each other. The packing nut and actuating stem are usually manufactured from steel so that if there was direct threaded contact between the actuating stem and packing nut, there could be undesirable galling between the corresponding threads. The necessity for using the bronze liner, while solving the problem of galling, has also added some manufacturing costs to the valve.
In addition, valves of the general type to which the subject invention is directed have employed rather complicated structural arrangements between the bifurcated inner end of the actuating stem and the valve needle to achieve desired non-rotation of the valve needle when the actuating stem was rotated relative to the valve body. These structural arrangements have typically included a cylindrical slot through the bifurcated inner end of the actuating stem with the valve needle having a corresponding spherical area at the outermost end thereof closely received in this cylindrical slot. Other arrangements have employed separate ball bearing means disposed between the bifurcated inner end of the actuating stem and the outer end of the valve needle. Both of these arrangements necessitated undesired special and difficult machining operations.
Because of the necessity for applying a compressive force to the sealing medium, the packing nut must be adjusted to a final position in the valve body so that the innermost end thereof would engage the alignment bushing to exert the desired compressive force against the sealing medium. The packing nut is threadedly received by the valve body so that once a final adjusted position has been obtained, it is desirable to retain the packing nut in that position with some assurance that it will not be moved therefrom. Accordingly, locking brackets have been utilized for this purpose and while some prior locking brackets have been known such as those shown in the commonly assigned U.S. Pat. Nos. 3,679,169 and 3,761,053, these prior brackets have had certain disadvantages. For example, prior brackets have generally been configured so that when the packing nut was in certain final adjusted positions, the body of the locking bracket would overhang the valve body thereby rendering it possible for clothing, tools, equipment and the like to catch thereon and cause possible injury or valve damage. Moreover, and due to the specifics of these prior locking bracket designs, they were not adjustable to the extent required to provide a full range of locking positions for the associated packing nuts.
Finally, the valve seat designs in the prior valve designs of the type to which the subject invention is directed have simply been defined by a relatively sharp lip positively engaged by the tip of the valve needle to achieve a valve closed position. During normal operation of the valves, the lip tends to become coined to the tip shape and, the higher the pressure of the fluid system, the greater the coining force. Eventually, at high system pressures, this results in a work hardened seat surface which is in an ultimate plastic state. This plastic state is unacceptable for effective and extended valve operation and life.
The present invention contemplates a new and improved article which overcomes all of the above referred to problems and others and provides a new high pressure valve which is relatively simple, more economical to manufacture, has a longer effective life at particularly high pressures and which may be readily adaptable to any number of uses in high pressure systems.